JAVA语言程序设计课后习题----第八单元解析（仅供参考）
1 本题主要考的是方法的克隆，与c++里面的拷贝有点相似，具体看书本p147
1 import java.util.Objects; 2 3 public class Square implements Cloneable{ 4 private int length; 5 6 public Square(int length) { 7 this.length = length; 8 } 9 10 @Override 11 public String toString() { 12 return "Square[" + 13 "length=" + length + 14 ']'; 15 } 16 17 @Override 18 public boolean equals(Object o) { 19 if (this == o) return true; 20 if (o == null || getClass() != o.getClass()) return false; 21 Square square = (Square) o; 22 return length == square.length; 23 } 24 25 @Override 26 public int hashCode() { 27 return Objects.hash(length); 28 } 29 30 public static void main(String[] args) throws CloneNotSupportedException{ 31 Square s1=new Square(100); 32 Square s2=(Square)s1.clone(); 33 System.out.println(s1==s2); 34 System.out.println(s1.equals(s2)); 35 System.out.println(s2.toString()); 36 37 } 38 }
2 本题水题，主要就是考数组，把产生的需求数存在数组里
1 public class Suiji { 2 public static int a[]=new int[6]; 3 public static void main(String[] args) { 4 Suiji s=new Suiji(); 5 System.out.println("随机产生1000个1-6的数"); 6 s.stc(6); 7 8 for (int i = 1; i <=6 ; i++) { 9 System.out.println(i+"的概率是"+(a[i-1]*1.0/1000)*100+"%"); 10 } 11 System.out.println("****************************"); 12 System.out.println("随机产生1000个1-1000的数"); 13 for (int i = 0; i < a.length; i++) { 14 a[i]=0; 15 } 16 s.stc(1000); 17 for (int i = 1; i <=6 ; i++) { 18 System.out.println(i+"的概率是"+(a[i-1]*1.0/1000)*100+"%"); 19 } 20 21 } 22 public void stc(int num){ 23 for (int i = 0; i <1000 ; i++) { 24 switch ((int)(Math.random()*num+1)){ 25 case 1:a[0]++; 26 break; 27 case 2:a[1]++; 28 break; 29 case 3:a[2]++; 30 break; 31 case 4:a[3]++; 32 break; 33 case 5:a[4]++; 34 break; 35 case 6:a[5]++; 36 break; 37 } 38 } 39 } 40 }
3 本题注意sinx x是弧度即可
1 public class Area { 2 public static void main(String[] args) { 3 float a=4.0f,b=5.0f; 4 5 float t= (float) Math.sin(30*(Math.PI/180)); 6 // System.out.println("三角形的面积为:"+(1*1.0/2)*a*b*t); 7 System.out.println(((1*1.0/2)*a*b*t)); 8 } 9 10 }
4 本题只要记得如何求最大值、最小值的封装方法即可（MAX_VALUE、MIN_VALUE）
1 public class Baozhuang { 2 // Integer integer; 3 public static void main(String[] args) { 4 Integer integer = null; 5 System.out.println("Integer的最大值"+integer.MAX_VALUE+"\t"+"Integer的最小值"+integer.MIN_VALUE); 6 Long l=null; 7 System.out.println("Long的最大值"+l.MAX_VALUE+"\t"+"Long的最小值"+l.MIN_VALUE); 8 Float f=null; 9 System.out.println("Float的最大值"+f.MAX_VALUE+"\t"+"Float的最小值"+f.MIN_VALUE); 10 Double d=null; 11 System.out.println("Double的最大值"+d.MAX_VALUE+"\t"+"Double的最小值"+d.MIN_VALUE); 12 Character character=null; 13 System.out.println(" Character的最大值"+character.MAX_VALUE+"\t"+" Character的最小值"+character.MIN_VALUE); 14 Byte b=null; 15 System.out.println(" Byte的最大值"+b.MAX_VALUE+"\t"+" Byte的最小值"+b.MIN_VALUE); 16 Short s=null; 17 System.out.println("Short的最大值"+s.MAX_VALUE+"\t"+" Short的最小值"+s.MIN_VALUE); 18 19 } 20 }
5 本题自行百度查看
6 本题水题，plusDays就是给当前对象增加几天
1 import java.text.ParseException; 2 import java.time.LocalDate; 3 public class ch06 { 4 public static void main(String[] args) throws ParseException { 5 LocalDate pday=LocalDate.of(2017,1,1).plusDays(256); 6 System.out.println(pday); 7 } 8 }
7 本题主要就是知道如何求天数，对什么值求模
1 import java.text.ParseException; 2 import java.text.SimpleDateFormat; 3 import java.util.Date; 4 import java.util.Scanner; 5 6 public class ch07 { 7 public static void main(String[] args) throws ParseException { 8 Scanner input =new Scanner(System.in); 9 String dbtime1 = input.next(); //第二个日期 10 String dbtime2 = input.next(); //第一个日期 11 //算两个日期间隔多少天 12 SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd"); 13 Date date1 = format.parse(dbtime1); 14 Date date2 = format.parse(dbtime2); 15 16 int a = (int) ((date1.getTime() - date2.getTime()) / (1000*3600*24)); 17 System.out.println(a); 18 } 19 }
8 本题具体自行查看书本p159
1 import java.time.LocalDate; 2 import java.time.format.TextStyle; 3 import java.util.Locale; 4 import java.util.Scanner; 5 6 public class PromtCalendar { 7 public static void main(String[] args) { 8 Scanner input = new Scanner(System.in); 9 System.out.println("输入一个年份(如2018)："); 10 int year = input.nextInt(); 11 12 for (int j = 1; j <=12; j++) { 13 // 返回本月第一天 14 LocalDate dates = LocalDate.of(year,j, 1); 15 String monthName = dates.getMonth().getDisplayName(TextStyle.FULL, Locale.getDefault()); 16 // 返回当月的天数 17 int dayOFmonth = dates.lengthOfMonth(); 18 System.out.println(year + "年 " + monthName); 19 System.out.println("-------------------------------"); 20 System.out.printf("%4s%3s%3s%3s%3s%3s%3s%n", "一", "二", "三", "四", "五", "六", "日"); 21 int dayOfWeek = dates.getDayOfWeek().getValue(); 22 for (int i = 2; i <= dayOfWeek; i++) { 23 System.out.printf("%4s", " "); 24 } 25 for (int i = 1; i <= dayOFmonth; i++) { 26 System.out.printf("%4d", i); 27 if ((dayOfWeek + i - 1) % 7 == 0) 28 System.out.println(); 29 } 30 System.out.println(); 31 } 32 } 33 }
9 本题主要考的数组里面值的存入问题，也可以用if语句逐一进行判断，注意要月份和天数都要满足
1 import java.util.Scanner; 2 3 public class xingzuo { 4 /* public static void main(String[] args) { 5 Scanner input = new Scanner(System.in); 6 System.out.println("输入一个年份(如2018)："); 7 int year=input.nextInt(); 8 int month = input.nextInt(); 9 // 输入天数 10 int day = input.nextInt(); 11 LocalDate dates3 = LocalDate.of(year, month, day).plusDays(30); 12 //dates3.plusDays(30); 13 System.out.println(dates3); 14 15 LocalDate[] desk = {LocalDate.of( 0,3, 20), LocalDate.of(0, 4, 20), 16 LocalDate.of(0, 4, 19), LocalDate.of(0, 4, 21), 17 LocalDate.of(0, 5, 20), LocalDate.of(0, 6, 22), 18 LocalDate.of(0, 6, 21), LocalDate.of(0, 7, 23), 19 LocalDate.of(0, 7, 22), LocalDate.of(0, 8, 23), 20 LocalDate.of(0, 8, 22), LocalDate.of(0, 9, 24), 21 LocalDate.of(0, 9, 22), LocalDate.of(0, 10, 24), 22 LocalDate.of(0, 10, 23), LocalDate.of(0, 11, 23), 23 LocalDate.of(0, 11, 22), LocalDate.of(0, 12, 22), 24 LocalDate.of(0, 12, 21), LocalDate.of(0, 1, 20), 25 LocalDate.of(0, 1, 19), LocalDate.of(0, 2, 19), 26 LocalDate.of(0, 2, 18), LocalDate.of(0, 3, 21)}; 27 28 29 if (dates3.isAfter(desk[0]) && dates3.isBefore(desk[1])) { 30 31 System.out.println("白羊座" ); 32 } 33 else if (dates3.isAfter(desk[2]) && dates3.isBefore(desk[3])){ 34 System.out.println("金牛座"); 35 } 36 else if (dates3.isAfter(desk[4]) && dates3.isBefore(desk[5])){ 37 System.out.println("双子"); 38 } 39 else if (dates3.isAfter(desk[6]) && dates3.isBefore(desk[7])){ 40 System.out.println("巨蟹"); 41 } 42 else if (dates3.isAfter(desk[8]) && dates3.isBefore(desk[9])){ 43 System.out.println("狮子"); 44 } 45 else if (dates3.isAfter(desk[10]) && dates3.isBefore(desk[11])){ 46 System.out.println("处女"); 47 } 48 else if (dates3.isAfter(desk[12]) && dates3.isBefore(desk[13])){ 49 System.out.println("天平"); 50 } 51 else if (dates3.isAfter(desk[14]) && dates3.isBefore(desk[15])){ 52 System.out.println("天蝎"); 53 } 54 else if (dates3.isAfter(desk[16]) && dates3.isBefore(desk[17])){ 55 System.out.println("射手"); 56 } 57 else if (dates3.isAfter(desk[18]) && dates3.isBefore(desk[19])){ 58 System.out.println("摩羯"); 59 } 60 else if (dates3.isAfter(desk[20]) && dates3.isBefore(desk[21])){ 61 System.out.println("水平"); 62 } 63 else if (dates3.isAfter(desk[22]) && dates3.isBefore(desk[23])){ 64 System.out.println("双鱼"); 65 } 66 }*/ 67 68 public static void main(String[] args) { 69 70 Scanner input = new Scanner(System.in); 71 System.out.println("请输入出生日期如（5 20）"); 72 System.out.println( 73 getConstellation(input.nextInt(),input.nextInt()) 74 ); 75 } 76 private final static int[] dayArr = new int[] { 20, 19, 21, 20, 21, 22, 23, 23, 23, 24, 23, 22 }; 77 private final static String[] constellationArr = new String[] { "摩羯座", "水瓶座", "双鱼座", "白羊座", "金牛座", "双子座", "巨蟹座", "狮子座", "处女座", "天秤座", "天蝎座", "射手座", "摩羯座" }; 78 public static String getConstellation(int month, int day) { 79 return day < dayArr[month - 1] ? constellationArr[month - 1] : constellationArr[month]; 80 } 81 }
